An appreciable fraction of oilfield services are provided by lowering tools down a well to perform particular tasks. Possible tasks include formation evaluation (e.g. logging in open hole and cased wells), opening and closing of valves, analyzing downhole fluids, taking fluid samples, removal of scale build-up (e.g. in producing wells). Some of the downhole oilfield tools are conveyed with cables of appropriate mechanical strength. Additionally, the cables may carry electrical power to the tools as well provide a communication link. Cables that carry power and provide downhole communication are generally called “wireline” cables.
However, because of cost constraints associated with wireline operations, many downhole applications use more simple cables that do not have electrical capability. These simple cables are typically called “slick line” cables. In slick line applications, the energy required to power the tool once it is down in the well generally comes from batteries that are included with or added to the tool. Nevertheless, the batteries are expensive, occupy a sizable amount of tool space, and are typically not very environmentally friendly.